BREAKING: LAST IOWA POLL OUT ROMNEY LEADS

Mitt Romney tops the latest Des Moines Register Iowa Poll in the closing days before the Iowa caucuses, but Ron Paul and Rick Santorum are poised within striking distance.

The poll, conducted Tuesday through Friday, shows support at 24 percent for Romney, the former governor of Massachusetts; 22 percent for Paul, a Texas congressman; and 15 percent for the surging Rick Santorum, a former U.S. senator from Pennsylvania.

But the four-day results don’t reflect just how quickly momentum is shifting in a race that has remained highly fluid for months. If the final two days of polling are considered separately, Santorum rises to second place, with 21 percent, pushing Paul to third, at 18 percent. Romney remains the same, at 24 percent.

“Momentum’s name is Rick Santorum,” said the Register’s pollster, J. Ann Selzer.

Another sign of the race’s volatility: 41 percent of likely caucusgoers say they could still be persuaded to change their minds.

Selzer & Co. of Des Moines conducted the poll of 602 likely Republican caucusgoers, which has a margin of error of plus or minus 4 percentage points. In the final two days of polling, 302 likely caucusgoers were interviewed, with a margin of error of plus or minus 5.6 percentage points.

The first-in-the-nation Iowa caucuses, which take place Tuesday evening, kick off voting in the presidential nominating process. The Iowa Poll, a Register exclusive since 1943, is a much-watched indicator of how candidates are faring in the leadoff caucus state.

The first three Iowa Polls of the 2012 caucus cycle, conducted in June, October and November, featured a different leader each time: first Romney, then retired business executive Herman Cain, then Gingrich. Other candidates took turns in the top tier, too. Bachmann was in second place to Romney in the June poll and won the Iowa straw poll in August. But her support plummeted this fall.

Gingrich surged to the lead with 25 percent support in the late November poll, but slid to 12 percent in the new poll.

Now, it’s Santorum’s time to rocket to the top tier. He has campaigned in Iowa more than any other candidate, stumping the state more than 100 days and conducting more than 300 events since the last presidential election. Next closest is Bachmann, at 80 days.

But until recent weeks, Santorum has struggled to escape single digits in state and national polls. He has campaigned as both a strong fiscal and social conservative, but social conservative voters had remained undecided or split among several candidates.

Romney campaigned lightly in the state until December, but he benefits from the network he built as a candidate four years ago, when he campaigned constantly and poured $10 million into a heavy advertising schedule and a big campaign organization.

Full coverage and analysis of the results will be published in the Des Moines Sunday Register and posted at DesMoinesRegister.com/caucus.